Estimating biomass production by tree component in Eucalyptus sp. clonal stands

Abstract

The improvement of forest production estimation is essential for utilizing planted forests as a renewable energy source. In this regard, the aim was to develop simultaneous models for estimating biomass production by tree component in clonal stands of Eucalyptus saligna and Eucalyptus grandis × Eucalyptus urophylla hybrids. Above-ground dry biomass was quantified in stands aged 7 years, in which allometric models were fitted independently to estimate the biomass of the stem, branches, leaves, and bark components at the tree level for E. saligna and E. grandis × E. urophylla. Simultaneous fits were made using seemingly unrelated regressions, aiming to ensure the additivity of the partial predictions by component to the estimation of total above-ground biomass. Statistical quality was assessed using error measures and graphical analysis. There was an improvement in the quality of the models for branch biomass for E. saligna and stem biomass for E. grandis × E. urophylla, compared to the independent fits. On the other hand, there was a reduction in the error in estimating the stem and bark components for E. saligna and stem and branches for E. grandis × E. urophylla. For both species, errors of less than 10% and the absence of trends in the estimate of total biomass were observed. The models developed via simultaneous equations showed statistically satisfactory results, especially for the stem component, which makes the greatest contribution to total biomass. Furthermore, there was an improvement in ensuring the additivity of the partial estimates in the estimation of total biomass.